The Doorking 1201-006 is a 4" UHMW sealed roller bearing V-wheel with a maximum weight of 750 lb. DKS DoorKing offers a variety of V-Wheels and V-Wheel assemblies used in slide gate applications that utilize an inverted "V" type track. The weight and usage of the gate is critical in determining the size and type of V-Wheel that is right for your gate. UHMW wheels are generally used for lighter gates while steel wheels are used for heavy gates. For very heavy gates, the tandem wheel assemblies are ideal and provide a long service life by spreading the weight of the gate across a larger area than a standard single wheel - much like the tandem wheels on airliners spread their weight across many wheels. When in doubt, it is always best to use a heavier-duty wheel.